Stock Repurchase Program - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Equity, Class of Treasury Stock [Line Items]
Stock repurchase during period, shares	6.1
Treasury stock purchased	$ 56,431,000	$ 150,445,000	$ 154,913,000
Average price of shares repurchased, per share	$ 9.29
Amount available under authorized stock repurchase program to repurchase outstanding shares of common stock	$ 183,300,000